Dental shade matching method and device

ABSTRACT

A method and device for determining the correct shade for porcelain crowns, composite fillings and other dental restorations comprising generating a light spectrum in at least two distinct wavelength spectra in sequence under the control of the operator of the light source generating the light spectrum with light in the first wavelength spectrum corresponding to daylight to enable the dentist or dental professional to perform a shade match the way a patient would view their restoration outside of a dental office in a real world environment and then switching to a second wavelength spectrum corresponding to either room light or ambient light.

BACKGROUND

Dentists always try to match the shade of a restoration to an existing tooth in the patients mouth. Historically, this takes place by bringing the patient to a nearby window using daylight as the light source. Literature suggests that the color temperature of 5500 degrees kelvin be used as a standard light spectrum that represents light on a cloudy bright day at 12 o'clock noon.

Some current devices use florescent lamps or LED's to produce a standard light spectrum of 5500 kelvin. However, when tooth shades are matched with the 5500 kelvin light spectra there still remains a significant chance the restoration shade will not match the existing tooth shade under different lighting conditions. There are very expensive spectrophotometers that aid in tooth shade selection. These devices typical sell for more than ten times the cost of our invention. However, they only measure the tooth shade at one wavelength spectra.

For example, the dentist matches the shade at 5500 degrees kelvin and it looks good in the dental office. The patient goes home and looks at their restoration in their bathroom light which happens to be an incandescent lamp. They then call the doctor to say the shade “changed”. This happens because what the doctor thought was a perfect match was only a good match but not perfect. In physics there is a principal called metamerism. Metamerism says that if a shade matches absolutely perfectly it should match in all color spectra, i.e., with all different light sources.

SUMMARY OF THE INVENTION

The shade matching method and device of the subject invention uses from 12 to 24 light emitting diodes (LED's) arranged in different groups each having a plurality of light emitting diodes (LED's) in a circular or rectangular array which is preferably concentric to one another. The preferred arrangement is two groups of an equal number of LED's in a circular array concentric to one another. For example, with just 12 LED's this device can produce three distinct color spectra to simulate different lighting conditions typically found in indoor and outdoor environments.

This method and device employs 12 to 24 LED's that can produce multiple wavelength spectra. By using 12 LED's our device produces three distinct wavelength spectra. A daylight color temperature of 5500 degrees Kelvin is typically seen in outdoors on a cloudy bright day. A warm white light of approximately 2800 to 3200 degrees kelvin represents incandescent lighting typically seen in homes, restaurants and offices. An ambient light in the range of 3400 degrees Kelvin to 4200 degrees kelvin is seen in mixed indoor environments where multiple light sources may be present. By turning on a set of 6-5500 degrees kelvin LED's the device produces a daylight spectra. By turning on a set of 6-3200 degrees kelvin the device produces lighting spectral typical of an incandescent indoor environment. By turning on 12 LED's, 6 with 3200 degree kelvin and 6 with 5500 degrees kelvin, the device produces a mixed ambient lighting spectra of approximately 3900 degrees Kelvin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of the device showing an array of 12 LED's in the head. The dotted lines show the internal batteries, a circuit board and on/off switch;

FIG. 2 shows an embodiment of the device of FIG. 1 using a 24 LED head and an on/off switch; and

FIG. 3 is a circuit schematic diagram of the electronic circuit in the circuit board of FIG. 1 for controlling the switching sequence of different groups of LED's for producing different distinct light color spectra under the control of the operator of the device.

DETAILED DESCRIPTION

The shade matching device in the present invention is illustrated in FIG. 1 and FIG. 2. it is a simple battery operated hand held device that uses multiple color matched LED's.

FIG. 1 shows the housing 8 of a hand held device with a battery compartment 6 and batteries 4 and 5. the head contains a viewing opening 2. A circuit board 6 controls the operation and sequencing of the LED conditions. The switch 3 turns the unit on and off. The head 7 houses the rest of the circuits board 3 and provide electrical connection to the LED's. in this iteration using 12 LED's, the grouping of LED's 1 represents one wavelength spectra, for example 5500 degrees kelvin. the grouping of LED's shown as 14, represents a second grouping of LED's for example, 3200 degrees kelvin. When both sets of LED's are on simultaneously, the combined wavelength spectra is 3900 degrees kelvin.

FIG. 2 shows a preferred version of this invention using 24 LED's. This version of the invention provides for four or five wavelength spectra. For example, this arrangement would provide 6 LED's in the 360-440 nanometer range. The six LED's in the 360-440 nanometer range can be arranged in line with one of the other groups of LED's, or with 3 LED's in each of two groups of LED's or arranged as a third group concentric to the other groups. Energy in the 360-440 nanometer range covers long wave U.V. and short wavelength visible light. In this spectral range normal teeth fluoresce. When restorations are made it is important to use materials that replicate the natural fluorescence of teeth so they look life like in lighting conditions where a small amount of the U.V. light spectrum is present, i.e.—outdoors or in stage or film lighting where the high color temperature of the light source used produces near U.V. energy. By providing the dentist with what a tooth shade looks like when exposed to long wave U.V. light, the material, i.e., ceramic, porcelain or composite. During the preparation of the restoration, i.e., crown can be then constructed to include small amounts of fluorescent material that will replicate the life like appearance of a natural teeth. In this version of my invention the sequence of light spectra would be as follows. In using this method depress the switch 13, LED string 1 (5500 degree Kelvin) turns on. Next, depress the switch a second time and LED string 1 is off and LED string 14 (3200 degree kelvin) turns on. Depress the switch 13 a third time and both string 1 and 14 go on simultaneously.

Depress switch 13 a fourth time, string 1 and 14 is off and string 20 (360-440 nanometers) turns on. Depress the switch 13 a fifth time and all LED's are off.

If desired, an additional light spectra can be made available by configuring a different combination of the 24 LED on/off grouping.

FIG. 3 shows a preferred electronic drive circuit for powering and controlling the functions of the LED's. The power supply is shown as 17, with a battery power source 3. Switch 13, can scroll though different combinations of LED wavelengths. The circuit contains a microprocessor 18, determines which LED's are on or off. It could also control additional LED's if desired. It should be understood that the angle of dispersion of each LED controls the focal distance of the generated light relative to the target dental restoration. 

What is claimed:
 1. A method for shade matching of teeth in the preparation of a porcelain, composite or any other tooth colored dental restoration for shade matching of teeth comprising the steps of directing light on the surface of teeth of a dental patient and for use in a dental laboratory setting using a light source adapted to produce at least two different wavelength spectra in sequence under the control of the operator of the light source with light at a first wavelength spectra corresponding to daylight approximating a color temperature of about 5500° K for initially comparing the shade of the tooth to be restored to selected color shades from a standard shade matching guide that shows different fixed color shades to establish a desired shade selection for the dental restoration at said first wavelength spectra and verifying the accuracy of the established shade selection by switching the wavelength spectra of the light source to a second wavelength spectra corresponding to either room light approximating a color temperature of about 3200° K or ambient light approximating a color temperature of about 3900° K.
 2. A method as defined in claim 1 wherein the light source is adapted to produce different multiple wavelength spectra in sequence under the control of the operator of the light source with light at a first wavelength spectra corresponding to daylight approximating a color temperature of about 5500° K, light and a second wavelength spectra corresponding to room light at about 3200° K and light at a third wavelength spectra representing ambient lighting at approximately 3900° K.
 3. A method as defined in claim 2 wherein the light source is adapted to produce light at a fourth wavelength spectra under the control of the operator of the light source in the 360-440 nanometer range to check for fluoresce of the restorative material which takes place within this wavelength range in natural teeth.
 4. A method as defined in claims 1 and 3 wherein the light source is switched from one wavelength spectra to another wavelength spectra in sequence under the control of the operator of the light source in a time period of less than about one minute.
 5. A method as defined in claim 4 wherein the light source consists of multiple groups of light emitting diodes including at least a first group of a plurality of light emitting diodes for generating light approximating about 5500° K, a second group of a plurality of light emitting diodes for generating light about 3200° K, and a control circuit for switching the operation of the different groups of light emitting diodes to operate the first group, the second group of LED's and the first and second group of LED's for simultaneously generating a mixed ambient light spectra of approximately 3900° K.
 6. A method as defined in claim 4 wherein the light source is switched from one wavelength spectra to another wavelength spectra such that light is generated in the following control sequence 5500° K, 3200° K, 3900° K and then in the 360-440 NM range.
 7. A dental color shading matching device for generating a multiple number of different wavelength spectra in sequence under the control of the operator of the light source so as to verify a shade selection when color matching teeth in the preparation of a porcelain, composite or any tooth colored restoration in the preparation of a dental restoration comprising a multiple number of light emitting diodes arranged to form at least two groups of light emitting diodes with each group having a plurality of light emitting diodes arranged in a closed geometrical pattern such that the light generated by each plurality of light emitting diodes will focus at a given target representing the tooth to be restored or tooth restoration over a given focal distance with each group of light emitting diodes generating a distinct color spectra inclusive of at least a first wavelength spectra corresponding to daylight approximating a color temperature of about 5500° K, and a second wavelength spectra corresponding to room light at about 3200° K and further comprising a common housing for the different groups of light emitting diodes. a source of power for all of the light emitting diodes and a control circuit enabling the operator of the device to switch on and off the different groups of light emitting diodes in a controlled sequence such that each group can be separately switched on or off as well as switching selected groups on simultaneously. 